Prosecutors say the singer claimed he completed four hours of trash pickup in Virginia, but records show he was on a plane to Mexico for part of that time. Brown's attorney disputes the allegations.

Los Angeles County prosecutors on Tuesday accused singer Chris Brown of failing to complete his court-ordered community service for his 2009 assault conviction and questioned whether the documents submitted as proof of his service were fraudulent.

A motion filed by the district attorney's office said that Brown claimed he completed four hours of trash pickup between 10 a.m. and 6 p.m. on one day when he was actually on a private plane to Cancun that he boarded at 4 p.m.

On another day that the entertainer said he was picking up trash in a Richmond, Va., alley, news photographers were snapping him 100 miles away in Washington, D.C., where he hosted a charity event that raised funds for the developmentally disabled, prosecutors contended.

Deputy Dist. Atty. Mary A. Murray outlined a series of inconsistencies with a report prepared by Richmond police about the number of hours Brown had served. She said a district attorney's investigation into Brown's community service claims found "significant discrepancies indicating at best sloppy documentation and at worst fraudulent reporting," and she asked a judge to order Brown to carry out his court-ordered labor in Los Angeles County instead of Virginia, where he lives.

Brown's attorney, Mark Geragos, disputed the allegations, accusing prosecutors of making "scurrilous, libelous and defamatory statements" against the R&B star. Geragos also disagreed with suggestions in supporting documents filed by the district attorney's office alleging that the defense attorney coached Virginia authorities in their conversations with Los Angeles County investigators.

"The motion is a disgrace, and the D.A. should be embarrassed, and I plan on asking for sanctions against the D.A.," Geragos said. "I also encourage the Richmond Police Department to take legal action against the L.A. district attorney."

Brown is on five years' probation after pleading guilty to a felony count of assault in connection with a 2009 attack on then-girlfriend Rihanna. As part of his probation, he was required to perform 180 days of community labor in Virginia.

The district attorney did not ask a judge to find Brown in violation of his probation. A judge will decide later whether Brown must serve additional community service time in Los Angeles County. If he does not fulfill his obligation to the court, he could be sent to jail.

The allegations by prosecutors add to the continuing problems that Brown is facing just days before Sunday's Grammy Awards; his album "Fortune" is one of the nominees.

The Los Angeles County district attorney's office said that Brown was the subject of a sheriff's investigation into a Jan. 27 fight at a West Hollywood recording studio where singer Frank Ocean was punched repeatedly by Brown and his friends. After the beating, Brown said, "We can bust on you too," the district attorney's motion alleged, noting that "bust" was slang for "shoot." Ocean declined to press charges, and sheriff's officials said they plan to close the case.

Last year in Miami, prosecutors said, Brown snatched a cellphone that a fan had used to take a photo of him and his then-girlfriend, telling the fan, "You're not going to put these pictures on a website," before driving off with the phone. The incident underscored the star's "anger-management problems" and at least amounted to petty theft, prosecutors said. Florida prosecutors declined to file charges against Brown.

Murray also cited a March 2011 incident at the "Good Morning America" studio in New York, where Brown became enraged when asked about his assault on Rihanna. Brown threw a chair through a window, an act that prosecutors said was "another demonstration of the defendant's anger-control issues and violent temper resulting in a violation of the law."

Brown, prosecutors said, has also violated his probation by smoking marijuana and failing to obtain permits to allow him to travel while on probation.

The latest allegations by the district attorney's office also focus attention on the Richmond Police Department, tasked with supervising the singer's community service requirements. In an August 2009 letter to the Los Angeles County court, Richmond Police Chief Bryan Norwood confirmed his department would oversee Brown's probation, saying the singer would be assigned "manual labor tasks, such as graffiti removal, trash pick up, washing cars, cleaning, maintaining grounds, etc."

But district attorney's investigators concluded that Richmond police rarely checked on Brown's progress, even though the chief wrote to the court in November 2011 vouching for Brown's completing more than 100 days of labor. Overtime records show that Richmond police officers provided Brown security at a concert performance, Murray wrote.